Alismacee. | FLORA OF TASMANIA. 43 
Very slender, floating herbs, inhabiting fresh-water. Leaves linear-elongate, 1-3 inches long, 1 line broad. 
Flowers moncecious, axillary, solitary, minute, hidden in the spathaceous axils of the leaves. Mare. A solitary, 
naked stamen, with short filament, and erect, quadrate, two- to four-celled anther. Pollen globose. FEMALE. 
Four ovaries in a spathe, sessile or pedicelled, with slender styles and peltate stigmas. Fruit of four linear-oblong, 
coriaceous, minute nuts, indehiscent, sometimes crenate at back, on long or short pedicels, furnished with long or 
short styles. Seed oblong, pendulous; testa membranous; albumen O; radicle very large; cotyledon doubled in- 
wards on the radicle. (Named in honour of John Jerome Zannichelli, a Venetian apothecary and botanist.) 
l. Zannichellia palustris (Linn. Sp. Pl. 1375).—Fl. N. Zeal. i. 237. ? Z. Preissii, Lehm. in Plant. 
Preiss. ìi. 3. (Gunn, 1564.) 
Has. Pools of fresh water, abundant: Hobarton, ete.—(v. v.) 
Disrris. Australia, New Zealand, Europe, North Africa, as far south as the Canaries, North, Central, 
and West Asia, India, east and west coasts of North America, and the West Indies. 
Gen. V. POSIDONIA, König. 
Flores hermaphroditi, spadice v. pedunculo basi spatha foliacea bilabiata incluso. Perianthium 0. 
Stamina persistentia, sessilia; antheris 3—4, bilocularibus, loculis discretis; filamentis crasse coriaceis, viri- 
dibus, erectis, conico-elongatis, utrinque extus basi loculum polliniferum gerentibus; polline confervoideo. 
Ovarium 1-loculare; ovulo 1, parietali, amphitropo ; stigmate sessili, villoso, lobato? Fructus subbaccatus, 
indehiscens. Semen longitudinaliter adnatum, exalbuminosum. Zmdryo macropodus; radicula maxima, 
infera; cotyledone inflexa, rima longitudinali inclusa.—Herbxe marine; caule repente, ramoso, foliorum ` 
exuviis vestito; foliis ad apices ramorum congestis, lineari-elongatis, gramineis ; spadice pedunculo crassius- 
culo e foliorum centro exserto. 
Dull-green plants, with creeping rhizomes, growing in salt-water.—Rhizomes short, shaggy with the fibrous 
remains of old leaves, and tufts of green, grassy leaves. The species are most common in tropical seas. Peduncle 
or spadiz short, arising from the centre of a leaf, its base enclosed in a two-valved, leafy spathe. Flowers few, 
three to twelve (each surrounded by a secondary spathe?). Perianth 0. Stamens three or four. Anthers placed 
at the back (outer face) of a broad, persistent, coriaceous filament, that resembles a segment of a perianth. Ovary 
one-celled, with one ovule. Fruit a small, fleshy utriculus, with a sessile, plumose stigma. Seed exalbuminous, 
attached on one side by all its length to the walls of the pericarp; radicle very large, bent upwards at the apex ? 
plumule lying in a slit of the cotyledon. —I have seen detached fruiting spikes of the Tasmanian species, in a very 
bad state; they were found by Gunn, washed up on the beach, and were supposed by him to belong to 
but they so closely accord with the general characters of the European P. oceanica, that I conclude they belonged 
to P. australis. (Name from Iloceıdwv, the god Neptune.) 
l. Posidonia australis (n. sp.); caule breviusculo, ramis abbreviatis exuviis foliorum longissimis 
flexuosis dense vestitis, foliis longissime linearibus obtusis, ligula brevissima truncata, spica 4-6-flora.— 
Caulinia oceanica, Br. Prodr. 339, non DC. (Gunn, 1347.) 
Has. Coast of Tasmania, Brown; near Georgetown, below low-water mark, Gunn. 
Disrris. South coast of Australia. 
Stems short; branches densely covered with long, ragged, white fibres, 2-3 inches long, the remains of old 
leaves. Leaves 2-3 feet long, 2 broad, rounded at the tip, nerveless, shining when dry. Ligula very short, decur- 
rent, and forming inflexed margins to the base of the leaf.—I have not seen the flowers of this plant, of which 
Mr. Brown says there are four to six on the spike; he refers it to the P. oceanica of the Mediterranean Seas, 
which is much smaller, with a stiff white brush at the base of the leaves, instead of long, matted fibres. Mr. 
Brown further remarks that the four to six flowers of this may distinguish it. 
